Dwight,
As the saying goes: "how fast do you want to go? = how much do you want to spend?"

There really are not many good options for the 380SE, if you want performance that is a case where you are much better off trading.

Option #1: The 300E is a different story. If the internals of the engine are in reasonably good shape you can do a twin-turbo kit good for approx 300HP/300lb-ft. You'd need to go 225/50/16 on the tires to harness the power, but for about $7500 or so for the turbo kit and another $1000-$1500 you can get wheels/tires. With the extra power you may want to consider the sportline suspension and a conversion to 400E front brakes. That will run you another $1500-$2000. When you are done with that you'd have a car that will probably 0-60 around 6 seconds flat and do the 1/4 somewhere in the high 14's to low 15's easy. Handling and braking will be similarly impressive. It should still be friendly enough for daily driver duty, but consider your resale screwed. Cash outlay of $11,000 for a "hot-rod benz" that would be a pretty serious performer.

Option #2 Sell and get a 400E. The 400E adds power but also more weight. There are two things you'd have to do to any 400E/E420 to get it to sports-sedan status. Those being more rubber and shorter gearing. Ditto for shoe size with the hot-rod 300E...225/50/16. It is the most rubber that will fit a normal W124 without bodywork mods. Given good wheels and tires the car is really MUCH MUCH more capable then when bone stock. That brings us to the second item, gearing. The stock 2.24 differential is WAY too tall for serious performance stuff. If you search the Shop Forum archives you should find mention to the appropriate ratio that will work out of the corporate parts bin. Given a 3.xx diff and the 225's you'd have a mean little sports sedan. The diff (new) would probably run $2,000 tops and the wheels and tires again around $1,500. So we are talking about $3,500 cash outlay + whatever the cost of the car is. A Brabus suspension kit would not be necessary, but it certainly would help! That would get you a car that performed as well as or better than the hot-rod 300E and nudged near a stock 500E's performance ballpark. (okay, when it was a hot day the 500E was performing under)

Option 3: Get a 500E. I've had a 91 300E, a 93 400E, and a 92 500E. There is no TRUE substitute for the real thing. No matter how hard you try (on any realistic budget), you will not be able to match what MB and Porsche did when teaming up on this car. Plus, in time you can always tune the 500E a bit. (search Shop Forum archives for references to 500E tuning...) I've timed my 92 500E on a approx 70 degree night as the following: 0-60 5.3 seconds, 1/4 mile 13.6@107.1mph The only mod off of stock was the switch to 235/50/16 tires in place of the stock 225/55/16's. On the racetrack that car would eat C5 vettes, about any stang or camaroach, etc. Those cars really are much meaner than their rated specs. The downsides to 500E's is a tendency to run hot and they are very temperature sensitive. You both gain and lose large amounts of HP/torque as ambient temp and engine temp changes. They can also suck gas and chew up tires (if driven aggressively) but that is par for the course on a car of that performance level. The 500E would cost more to begin with, but it should hold its value much better than either of the others. You also will not have to spend as much to get it to a serious performance level. With the exception of the odd tuner car (damn 1/3rd of a million dollar Renntech V12 comes to mind) the 500E's pretty much were king of Starfest acceleration events.

One other option does come to mind. Pick up a 190 16v with a bum engine and go to town. A performance rebuilt to 2.5 liters is good for 235HP and a similar bump in torque. (cost approx $4500) Then my personal twist would be to add a Eaton style supercharger ala SLK/C230K. Given the similar engine architecture (DOHC, 4-vavles per cyl, 4-cyl of approx same displacement, etc) I bet the same Eaton used on the SLK would really help the torque characteristics of the 4-cyl a bunch. With the "kompressor" you are probably talking somewhere in the neighborhood of 275HP minimum. Bolt on some 225/45/16 wheels and tires and you have a midget muscle-car that can handle like a fiend as well.

Let me know what your performance goals, budget, and other general preferences are and I'll be happy to continue the discussion.

Hope this helps...Lee